Battery pack

ABSTRACT

A battery pack may include a drainage device provided at a bottom portion of the housing case. The drainage device may include a drain hole communicating between the inside and the outside of the housing case, so that water introduced into the housing case is discharged to the outside of the housing case. The drainage device may be disposed between two of the terminal members that are connected to electrodes of the battery cells.

This application is a Continuation application of U.S. application Ser.No. 13/860,208 filed Apr. 10, 2013, which is a Continuation of PCTApplication No. PCT/JP2011/073073 filed Oct. 6, 2011, which claimspriority from Japanese Application No. 2010-290018 filed Dec. 27, 2010and Japanese Application No. 2010-247214 filed Nov. 4, 2010. Thedisclosure of each of the earlier applications is incorporated herein byreference in its entirety.

TECHNICAL FIELD

Embodiments of the present invention relates to a battery packconfigured to be capable of being mounted to a tool body of an electrictool as a power source of the electric tool.

BACKGROUND ART

In the related art, an electric tool includes a tool body driven byelectric power, and a battery pack that serves as a power source for thetool body. The battery pack is configured to be detachably mounted tothe tool body. The battery pack includes a housing case that forms anexterior cover, and a battery body that is installed in the housingcase. The battery body includes a plurality of battery cells that can becharged and discharged, and a control board that controls the charge anddischarge operations. Lead plates are connected to electrodes of theplurality of battery cells so that the battery cells are electricallyconnected in series or in parallel to each other.

Meanwhile, there may be an occasion that the afore-mentioned electrictool is used outdoors. Therefore, water such as raindrops may besplashed on such a battery pack, so that water may enter into thehousing case. Here, when water enters into the housing case to cause theabove-mentioned lead plates to be soaked in the water, unintended leadplates may be electrically connected to each other to the result thatelectricity, which is charged in battery cells, leaks.

For this reason, among battery packs, a battery pack has been known thatis provided with a drain hole at a bottom portion of a housing case inorder to discharge the water, which has been entered into the housingcase, to the outside of the housing case (for example, seeJP-A-2006-196277). According to this battery pack, it is possible todrain the water, which has been entered into the housing case, to theoutside of the housing case from the drain hole, and therefore, it ispossible to avoid the soaking of the lead plates in water, so thatelectricity charged in the battery cells may not leak.

Incidentally, in order to improve the drainage effect described above,it has been considered to provide a plurality of the drain holes formedat the bottom portion of the housing case.

However, if the plurality of drain holes are merely formed at the bottomportion of the housing case, conversely, water or dust may easily enterinto the housing case from the drain holes. For this reason, it ispreferable that the number of the drain holes is as small as possible,while the drainage effect described above is enhanced.

It is an object of the invention to provide a battery pack that isconfigured to be capable of being mounted on a tool body of an electrictool as a power source of the electric tool, can efficiently drain waterhaving been introduced into a housing case to the outside of the housingcase so as to prevent the leakage of the electricity charged in batterycells, and can make the number of drain holes be as small as possible.

SUMMARY OF THE INVENTION

In one aspect according to the present teachings, a battery pack mayinclude a drainage device provided at a bottom portion of the housingcase. The drainage device may include a drain hole communicating betweeninside and outside of the housing case, so that water introduced intothe housing case is discharged to the outside of the housing case. Thedrainage device may be disposed at least between two of terminal membersthat are connected to electrodes of the battery cells.

According to a first embodiment, there is provided a battery packconfigured to be able to be mounted on a tool body of an electric toolas a power source of the electric tool. The battery pack has a housingcase forming an outer cover and a plurality of battery cells disposed inthe housing case. A drainage function-shape portion is provided at abottom portion of the housing case and includes a drain holecommunicating with the inside of the housing case and the outside of thehousing case for discharging water. which has been introduced into thehousing case, to the outside of the housing case. An arrangementposition of the drainage function-shape portion is set to be present atleast between terminal members connected to electrodes of the batterycells.

Here, the drainage function-shape portion may include a drain holecommunicating between the inside of the housing case and the outside ofthe housing case. This means that the drainage function-shape portionmay be formed of only the drain hole or may include the drain hole and astructure that guides water to the drain hole.

According to the battery pack of the first embodiment, since thearrangement position of the drainage function-shape portion, which isdisposed at the bottom portion of the housing case, is set to be presentat least between the terminal members connected to the electrodes of thebattery cells, it is possible to discharge water, which is presentbetween the terminal members, to the outside of the housing case fromthe inside of the housing case. Accordingly, it is possible to drainwater so that water presented at least between the terminal members isremoved. As a result, it is possible to prevent the electricalconnection between the terminal members, which may be caused when theterminal members soak in water. That is, even in the case that anappropriate rib shape is formed in the housing case for supporting thebattery cells, it is possible to prevent electrical connection, whichmay be caused when at least the terminal members soak in the water,while allowing a puddle to be formed by the rib shape.

Accordingly, it is possible to prevent unintended electrical connectionbetween the terminal members, which may be caused when the terminalmembers become soaked in water. That is, it is possible to efficientlydrain water, which has been introduced into the housing case, to theoutside of the housing case so that leakage of the electricity chargedin the battery cells is prevented. Further, since the drain holes to bearranged are suppressed to minimal positions where the unintendedelectrical connection between the terminal members can be prevented, itis possible to make the number of drain holes be as small as possible.

According to a second embodiment, in the battery pack according to thefirst aspect, the terminal members, between which the arrangementposition of the drainage function-shape portion is set, are terminalmembers that have a mutually adjacent arrangement relationship along anadjacently arranged direction of the electrodes of the plurality ofbattery cells. The battery cells are arranged in parallel so that theelectrodes are arranged adjacent to each other, and have electricalpotentials different from each other.

With the battery pack of the second embodiment, the terminal members,between which the arrangement position of the drainage function-shapeportion is set, are terminal members which have a mutually adjacentarrangement relationship and have electrical potentials different fromeach other. Accordingly, a position where water is to be drained, can beset to be between the terminal members having a mutually adjacentarrangement relationship and have electrical potentials different fromeach other. Therefore, it is possible to set a position where it isdesirous to drain and remove water for maintaining an insulation state,to a position where a short circuit between the terminal members is aptto occur, so that it is possible to more reliably prevent a shortcircuit, which may be caused when the terminal members soak in water.

According to a third embodiment, in the battery pack according to thefirst or second embodiment, an outer end edge of the drain hole disposedon an outer side of the housing case is formed and set to have a shapeso that the outer end edge rises toward the inside of the housing caseas compared to at least a peripheral portion of the outer end edge.

With the battery pack of the third embodiment, the outer end edge of thedrain hole disposed on an outer side of the housing case is formed andset to have a shape so that the outer end edge rises toward the insideof the housing case as compared to at least the peripheral portion ofthe outer end edge. Accordingly, even in the case that the battery packmounted on the tool body is placed on a desk or the ground and thebottom portion of the battery pack comes into contact with a placementsurface of the desk or the ground, the outer end edge of the drain holeis positioned above the placement surface. Therefore, since it ispossible to prevent the drain hole from being closed by the placementsurface, it is possible to discharge the water, which is introduced intothe housing case, to the outside of the housing case from the drainhole.

In addition, since it is possible to form at least a small clearancebetween the outer end edge of the drain hole and the placement surface,it is possible to easily guide the water, which is present in thehousing case, to the outside of the housing case by utilizing thesurface tension of the water introduced into the clearance. Accordingly,it is possible to efficiently drain the water, which has been introducedinto the housing case, to the outside of the housing case.

According to a fourth embodiment, in the battery pack according to anyone of the first to third embodiments, the drainage function-shapeportion includes a flow guide device for guiding the flow of water sothat water flows toward the drain hole, and the flow guide device isformed as a drain passage, so that the bottom portion of an inner sideof the housing case is inclined downward toward the lower side of thebottom portion along a direction toward the drain hole.

With the battery pack of the fourth embodiment, since the flow guidedevice is formed as a drain passage, so that the bottom portion of aninner side of the housing case is inclined downward toward the lowerside of the bottom portion along a direction toward the drain hole, itis possible to make the water, which has been introduced into thehousing case, flow toward the drain hole by the inclined structure ofthe drain passage. Accordingly, it is possible to improve the drainageperformance of not only the periphery of the drain hole but also aportion forming the drain passage, so that it is possible to expand arange, for which it is desired to improved the drainage performance.

Meanwhile, the arrangement portion where the drain passage is arrangedmay be present between the terminal members that are connected to theelectrodes of the battery cells, or may be present at a position otherthan the position between the terminal members. Further, the drainpassage may be formed to be inclined relative to the inner surface ofthe bottom portion, and may be formed flush with the outer surface ofthe bottom portion.

According to a fifth embodiment, in the battery pack according to anyone of the first to fourth embodiments, the drainage function-shapeportion includes a draw guide device for guiding the draw of water sothat water is collected toward the drain hole, and the draw guide deviceis formed as a drawing groove that extends in a concave groove shapealong an inner surface of the housing case from an inner end edge of thedrain hole disposed on an inner side of the housing case, and acts so asto draw water toward the drain hole.

With the battery pack of the fifth embodiment, the draw guide device isformed as a drawing groove that extends in a concave groove shape alongan inner surface of the housing case from an inner end edge of the drainhole disposed on an inner side of the housing case, and acts so as todraw water toward the drain hole.

Accordingly, it is possible to make the complete drainage of the water,which is present between the terminal members, so as to affect to theperipheral portion of the drain hole. Therefore, it is possible to morereliably prevent the electrical connection between the terminal members,which may be caused when the terminal members are soaked in water.

According to a sixth embodiment, in the battery pack according to anyone of the first to fifth embodiments, a foreign material-introductionrestricting rib is provided in the housing case so as to cross anopening shape of the drain hole in the housing case while maintaining anopened state of the drain hole.

With the battery pack of the sixth embodiment, the foreignmaterial-introduction restricting rib is provided in the housing case soas to cross an opening shape of the drain hole in the housing case.Accordingly, even in the case that foreign materials are likelyintroduced into the housing case from the outside of the housing casethrough the drain hole, it is possible to hinder the introduction of theforeign materials by the foreign material-introduction regulating rib.Therefore, it is possible to maintain a clean inside of the housingcase.

According to a seventh embodiment, in the battery pack according to anyone of the first to sixth embodiments, an arrangement position of thedrain hole is set to be present between the terminal members, and anarrangement position of any one or both of the flow guide device and thedraw guide device is set to a position that is different from theposition set between the terminal members. According to the battery packof the seventh aspect, since the arrangement position of the drain holeis set to be present between the terminal members, it is possible todrain the water, which is present between the terminal members, to theoutside of the housing case from the inside of the housing case.Accordingly, it is possible to guide the water, which is present in thevicinity of the drain hole, to the drain hole by the flow guide deviceor the draw guide device and to completely remove the water, which ispresent between these terminal members, by the presence of the drainhole. Therefore, it is possible to reliably prevent the unintendedelectrical connection between the terminal members.

According to an eighth embodiment, in the battery pack according to anyone of the first to sixth embodiments, at least a part of any one orboth of the flow guide device and the draw guide device is set to bepresent between the terminal members, and an arrangement position of thedrain hole is set to a position that is different from the position setbetween the terminal members.

With the battery pack of the eighth embodiment, the arrangement positionof the drain hole is set to a position that is different from theposition set between the terminal members, and at least a part of anyone or both of the flow guide device and the draw guide device is set tobe present between the terminal members. Accordingly, the arrangementposition of the drain hole can be set to a suitable portion of thehousing case according to the design of the battery pack, while it ispossible to drain water, which is present between these terminalmembers, to the outside of the housing case from the inside of thehousing case. Therefore, it is possible to increase the degree offreedom of the arrangement position of the drain hole, so that it isalso possible to increase the degree of freedom in the design of thebattery pack.

Further, according to a ninth embodiment, in the battery pack accordingto the first embodiment, the housing case forming the outer cover of thebattery pack is provided with a communication opening that communicateswith the inside of the housing case from the outside of the housingcase, and the housing case is provided with a water-introductionrestricting portion that restricts the introduction of water, which ispresent in the vicinity of the communication opening, into thecommunication opening.

With the battery pack of the ninth embodiment, the housing case isprovided with a water-introduction restricting portion that restrictsthe introduction of the water, which is present in the vicinity of thecommunication opening, into the communication opening, and therefore,the water-introduction regulating portion can restrict the introductionof water into the communication opening. Accordingly, it is possible toimprove the waterproof property of the battery pack by restricting theintrusion of water into the housing case from the outside of the housingcase.

According to a tenth embodiment, in the battery pack according to theninth aspect, the water-introduction restricting portion is configuredto have an inclined structure that makes water, which is present in thevicinity of the communication opening, flow in a direction away from thecommunication opening.

With the battery pack of the tenth embodiment, since thewater-introduction restricting portion is configured to have an inclinedstructure that makes water, which is present in the vicinity of thecommunication opening, flow in a direction away from the communicationopening, it is possible to make the water, which is present in thevicinity of the communication opening, flow in the direction away fromthe communication opening by the inclined structure of thewater-introduction restricting portion. Accordingly, it is possible torestrict the introduction of water into the housing case from theoutside of the housing case by isolating water from the communicationopening, so that it is possible to improve the waterproof property ofthe battery pack.

According to an eleventh embodiment, in the battery pack according tothe tenth embodiment, a battery-side connection terminal that iselectrically connected to a connection terminal provided on a mountingtarget when the battery pack is mounted on the mounting target such asthe tool body, wherein the communication opening is positioned at anarrangement portion where the battery-side connection terminal isarranged, and the water-introduction restricting portion is set for theperiphery of the arrangement portion of the battery-side connectionterminal, which is set to be the vicinity of the communication opening.The mounting target may be, for example, a tool body that is driven bythe electric power, or a dedicated charger that is used during charging.

With the battery pack of the eleventh embodiment, since thewater-introduction restriction portion is set for the periphery of thearrangement portion of the battery-side connection terminal, it ispossible to make the water, which is present in the vicinity of thearrangement portion of the battery-side connection terminal, flow in thedirection away from the periphery of the arrangement portion of thebattery-side connection terminal using the inclined structure of thewater-introduction restricting portion. Accordingly, it is possible toseparate water from the arrangement portion of the battery-sideconnection terminal, and therefore, it is possible to improve thewaterproof property of the battery pack by restricting the intrusion ofwater into the housing case from the outside of the housing case, sothat it is possible to make the contact between water such as raindropsand the battery-side connection terminal more difficult.

According to a twelfth embodiment, the water-introduction restrictingportion is formed in an uneven shape that isolates the water, which ispresent in the vicinity of the communication opening, from thecommunication opening.

With the battery pack of the twelfth embodiment, since thewater-introduction restricting portion is formed in an uneven shape thatisolates the water, which is present in the vicinity of thecommunication opening, from the communication opening, it is possible toisolate water, which is present in the vicinity of the communicationopening, from the communication opening by the uneven shape of thewater-introduction restricting portion. Accordingly, it is possible torestrict the intrusion of water into the housing case from the outsideof the housing case by isolating water from the communication opening,so that it is possible to improve the waterproof property of the batterypack.

Here, the “uneven shape” may include, for example, a convex wallstructure having ribs in the shape of a protrusion, a concave groove, orany appropriate uneven step shape, or the like. It may also include anyof a concave shape, a convex shape, and an uneven shape that function toisolate the water, which is present in the vicinity of the communicationopening, from the communication opening.

In a thirteenth embodiment, constructed similar to a battery pack of thetwelfth embodiment, a male hook portion is fitted to a female hookportion provided on a mounting target when the battery pack is mountedon a mounting target such as the tool body. The communication opening isset to an arrangement portion where the male hook portion is arranged,and the water-introduction restricting portion is provided as theperiphery of the arrangement portion of the male hook portion. Suchwater-introduction restricting portion is set to be the vicinity of thecommunication opening.

With the battery pack of the thirteenth embodiment, since thewater-introduction restricting portion is provided for on the peripheryof the arrangement portion of the male hook portion, it is possible toisolate the water, which is present in the periphery of the arrangementportion of the male hook portion, from the arrangement portion of themale hook portion, by the uneven shape of the water-introductionrestricting portion. Accordingly, it is possible to restrict theintroduction of water into the housing case from the outside of thehousing case by isolating water from the arrangement portion of the malehook portion, so that it is possible to improve the waterproof propertyof the battery pack.

According to a fourteenth embodiment, in the battery pack according tothe twelfth embodiment, there is provided a vent hole through which airflows into the housing case from the outside of the housing case,wherein the communication opening is set to an arrangement portion wherethe vent hole is arranged. The water-introduction restricting portion isprovided on the periphery of the arrangement portion of the vent hole,which is set to be the periphery of the communication opening.

With the battery pack of the fourteenth embodiment, since thewater-introduction restricting portion is provided on the periphery ofthe arrangement portion of the vent hole, it is possible to isolate thewater, which is present in the periphery of the arrangement portion ofthe vent hole, from the arrangement portion of the vent hole by theuneven shape of the water-introduction restricting portion. Accordingly,it is possible to restrict the introduction of water into the housingcase from the outside of the housing case by isolating water from thearrangement portion of the vent hole portion, so that it is possible toimprove the waterproof property of the battery pack.

Advantageous Effects of Embodiments

According to the battery pack of the first embodiment, it is possible toefficiently drain water, which has been introduced into the housingcase, to the outside of the housing case so as to prevent the leakage ofthe electricity charged in battery cells, and to make the number ofdrain holes be as small as possible.

According to the battery pack of the second embodiment, it is possibleto set a position, for which it is desirous to maintain an insulationstate, to a position where a short circuit between the terminal memberseasily occurs, and therefore, it is possible to more reliably prevent ashort circuit.

According to the battery pack of the third embodiment, it is possible toprevent the drain hole from being closed by the placement surface, andtherefore, it is possible to easily guide the water, which is present inthe housing case, to the outside of the housing case.

According to the battery pack of the fourth embodiment, it is possibleto improve the drainage performance of not only the periphery of thedrain hole but also a portion forming the drain passage, so that it ispossible to expand a range, for which it is desired to improved thedrainage performance.

According to the battery pack of the fifth embodiment, it is possible tomore reliably prevent the electrical connection between the terminalmembers, which may be caused when the terminal members soak in water.

According to the battery pack of the sixth embodiment, it is possible tomaintain the inside of the housing case clean.

According to the battery pack of the seventh embodiment, it is possibleto completely remove water, which is present between the terminalmembers, by the presence of the drain hole, so that it is possible toreliably prevent the unintended electrical connection between theterminal members.

According to the battery pack of the eighth embodiment, it is possibleto increase the degree of freedom of the arrangement position of thedrain hole, so that it is also possible to increase the degree offreedom in the design of the battery pack.

According to the battery pack of the ninth embodiment, it is possible torestrict the introduction of water into the housing case from theoutside of the housing case, so that it is possible to improve thewaterproof property of the battery pack.

According to the battery pack of the tenth embodiment, it is possible torestrict the introduction of water by isolating water from thecommunication opening, so that it is possible to improve the waterproofproperty of the battery pack.

According to the battery pack of the eleventh embodiment, it is possibleto improve the waterproof property of the battery pack, so that it ispossible to make the contact between water such as raindrops and thebattery-side connection terminal more difficult.

According to the battery pack of the twelfth embodiment, theintroduction of water into the housing case from the outside of thehousing case is restricted by isolating water from the communicationopening. Accordingly, the waterproof property of the battery pack isimproved.

According to the battery pack of the thirteenth embodiment, theintroduction of water is restricted by isolating water from thearrangement portion of the male hook portion. Accordingly, thewaterproof property of the battery pack is improved.

According to the battery pack of the fourteenth embodiment, theintroduction of water is restricted by isolating water from thearrangement portion of the vent hole. Accordingly, the waterproofproperty of the battery pack is improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded perspective view of a battery pack of a firstembodiment that is embodied in a first example.

FIG. 2 is a bottom view of the battery pack of FIG. 1 when seen from thebottom.

FIG. 3 is a cross-sectional view of the battery pack taken along lineIII-III in FIG. 2.

FIG. 4 is a cross-sectional view of the battery pack taken along lineIV-IV in FIG. 2.

FIG. 5 is a cross-sectional view of the battery pack taken along lineV-V in FIG. 2.

FIG. 6 is an enlarged cross-sectional view of an arrangement portion ofa case body of FIG. 5 where a drain hole is arranged.

FIG. 7 is a top view of the case body that is seen from the top so thatthe inside of the case body is seen.

FIG. 8 is an enlarged top view of the arrangement portion of the casebody where the drain hole is arranged.

FIG. 9 is a cross-sectional view of a battery pack showing an examplewhere drain passages are provided.

FIG. 10 is an enlarged top view of the drain hole showing an examplewhere drawing grooves are provided.

FIG. 11 is a perspective view of the case body that is seen inperspective so that the inside of the case body is seen.

FIG. 12 is a cross-sectional view of the case body taken along lineXII-XII in FIG. 11.

FIG. 13 is a perspective view of the appearance of a battery pack of athird embodiment that is embodied in a second example.

FIG. 14 is a top view of the battery pack of FIG. 13.

FIG. 15 is a cross-sectional view of the battery pack taken along lineXV-XV in FIG. 14.

FIG. 16 is a cross-sectional view of the battery pack taken along lineXVI-XVI in FIG. 14.

FIG. 17 is an enlarged cross-sectional view of the upper surface of thebattery pack shown in FIG. 16.

FIG. 18 is a perspective view of the appearance of a battery pack of afourth embodiment that is embodied in the second example.

FIG. 19 is a top view of the battery pack of FIG. 18.

FIG. 20 is a cross-sectional view taken along line XX-XX in FIG. 19.

FIG. 21 is a cross-sectional view taken along line XXI-XXI in FIG. 19.

DETAILED DESCRIPTION OF THE INVENTION

First and second embodiments, which are embodied in a first exampleshown in FIGS. 1 to 12, will be described below.

First Embodiment

The first embodiment, which embodies a battery pack according to theinvention, will be described below with reference to FIGS. 1 to 10.

An exploded perspective view of FIG. 1 shows a battery pack 10 of afirst embodiment that is embodied in a first example. This explodedperspective view shows the battery pack 10 so that the inside of abattery pack body 40 is seen. Meanwhile, in the following description,an electrical connection side of the battery pack 10 will be defined asthe upper side and a slide mounting direction of the battery pack 10will be defined as a forward direction.

The battery pack 10 is configured to be detachably mounted by slidingonto a tool body (mounting target) of an electric tool that is typifiedby, for example, an electric screwdriver. The battery pack 10 serves asa drive power source of the tool body having on the battery pack 10mounted thereon. For this reason, when the charge amount of the batterypack 10 is reduced, the battery pack 10 is removed from the tool bodyand charged by a dedicated external charger (mounting target), and whenit is completely charged by the dedicated charger, the battery pack 10is remounted on the tool body and functions as a drive power source.

As shown in the exploded perspective view of FIG. 1, the battery pack 10generally includes a housing case 20 and a battery pack body 40. Thehousing case 20 is formed in the shape of a case in which the batterypack body 40 is disposed and which forms an outer cover. Further, thebattery pack body 40 is mounted within the housing case 20.

Prior to the description of the housing case 20, the structure of thebattery pack body 40 will be described.

The battery pack body 40 is disposed in the housing case 20 described indetail below and generally includes a plurality of battery cells 41, aconnection control board 51, and a male hook mechanism 55 as shown inFIG. 1.

The battery cells 41 are battery cells that are broadly used and can becharged and discharged. As shown in FIG. 1, the battery cells 41 of thebattery pack body 40 are disposed in parallel so that a total of tenbattery cells 41 form two stages each of which includes five batterycells and electrodes 42 of the battery cells 41 are adjacent to eachother. Specifically, a total of ten battery cells 41 are arranged sideby side to form two stages each having five battery cells, so that theelectrodes 42 of the battery cells 41 are positioned on both the leftand right sides of the battery pack. Meanwhile, for the purpose ofexplanation of the battery cells 41 arranged side by side in this way,the battery cells 41 are denoted by reference numerals as a firstbattery cell 410, a second battery cell 411, a third battery cell 412, afourth battery cell 413, . . . in this order from the upper side and thefront side of the battery pack 10. Further, a lead base end of a leadwire of the electrode 42 of each battery cell 41, which is shown in thedrawing, is shown as a circular mark in a lead plate 45. However, thislead wire is led from an end portion of the battery cell 41 that ispositioned at the circular mark of the lead plate 45.

The electrodes 42 of the battery cells 41, which have been arranged sideby side as described above, are positioned at both left and right endsof the battery pack 10. That is, ten electrodes 42 of the respectivebattery cells 41 are positioned at each of both left and right ends ofthe battery pack 10. Lead plates 45, which are to be electricallyconnected, are mounted on the respective electrodes 42 of these batterycells 41. Specifically, left lead plates 46, which are electricallyconnected, are mounted on the electrodes 42, which are positioned at theleft ends, of the ten battery cells 41; right lead plates 47, which areelectrically connected, are mounted on the electrodes 42, which arepositioned at the right ends, of the ten battery cells 41. These leftand right lead plates 46 and 47 correspond to terminal members accordingto the invention, and function as plate-like terminals that are broadlyused. Moreover, the other sides of the lead plates 45 (the left andright lead plates 46 and 47) of which one sides are connected to theelectrodes 42 of the battery cells 41 in this way are electricallyconnected to the connection control board 51 that will be describedbelow. Meanwhile, these left and right lead plates 46 and 47 will bedescribed in detail later.

Next, the connection control board 51 and the male hook mechanism 55will be described.

The connection control board 51 is electrically connected to the batterycells 41 that can be charged and discharged, and controls the charge anddischarge of the battery cells 41. That is, the connection control board51 is disposed above the above-mentioned plurality of battery cells 41,and generally includes a control board 52 and connection terminalportions 53 that are provided on the control board 52. The control board52 performs appropriate electrical controls when the battery cells 41are charged and discharged. The connection terminal portions 53 serve asterminals that are electrically connected to a tool body or a dedicatedcharger (not shown) serving as a mounting target. That is, theconnection terminal portions 53 include three kinds of connectionterminals, that is, a positive connection terminal 531 that is connectedto a positive terminal of, for example, the tool body serving as themounting target; a negative connection terminal 532 that is connected toa negative terminal of, for example, the tool body; and a controlconnection terminal 533 that is connected to a control terminal of, forexample, the tool body. Meanwhile, these connection terminal portions 53are formed by leaf spring-type metal terminals that are disposed so asto face each other.

The male hook mechanism 55 has the structure that is removably locked tothe tool body when sliding to be mounted on, for example, the tool bodyserving as the above-mentioned mounting target. For this reason, themale hook mechanism 55 has a hook shape for locking to the tool body anda finger-engaging shape for a release operation. Specifically, the malehook mechanism 55 includes a hook-type structure 56 that has the hookshape and the finger-engaging shape and a biasing spring 57 that biasesthe hook-type structure 56 in a locking direction. The male hookmechanism 55 having the above-mentioned structure automatically locksthe hook-type structure 56 to the tool body by a biasing force of thebiasing spring 57 when slid to be mounted on the tool body. Further,when a release operation is performed against the biasing force of thebiasing spring 57, the locking of the hook-type structure 56 to the toolbody is released. When the battery pack 10 is slid in this state, themale hook mechanism 55 can be removed from the tool body.

Next, the above-mentioned left and right lead plates 46 and 47 will bedescribed in detail.

The left and right lead plates 46 and 47 are formed of plate-liketerminals, respectively, and are mounted over the electrodes 42 of theplurality of battery cells 41, respectively.

A bottom view of FIG. 2 shows the battery pack 10 that is seen from thebottom. A cross-sectional view of FIG. 3 shows the cross-section of thebattery pack 10 of FIG. 2 taken along line III-III so that the left leadplates 46 positioned on the left side of the battery pack 10 are seen. Across-sectional view of FIG. 4 shows the cross-section of the batterypack 10 of FIG. 2 taken along line IV-IV so that the right lead plates47 positioned on the right side of the battery pack 10 are seen.

As shown in FIG. 3, the left lead plates 46 are formed of threeplate-like terminals that are separated from each other. The three leftlead plates 46 are denoted by reference numerals as a first left leadplate 461, a second left lead plate 462, and a third left lead plate 463in this order from the front side. That is, as shown in FIG. 3, thefirst left lead plate 461 is mounted to extend between the two leftelectrodes 42 of the first battery cell 410 and the second battery cell411 among ten electrodes 42 that are formed at the left ends of thebattery cells 41. Further, the second left lead plate 462 is mounted toextend between the four left electrodes 42 of the third battery cell412, the fourth battery cell 413, the fifth battery cell 414, and thesixth battery cell 415. Furthermore, the third left lead plate 463 ismounted to extend between the four left electrodes 42 of the seventhbattery cell 416, the eighth battery cell 417, the ninth battery cell418, and the tenth battery cell 419.

Meanwhile, conversely, as shown in FIG. 3, the first and second leftlead plates 461 and 462 are arranged and constructed to form a separateconfiguration such that the first and second battery cells 410 and 411and the third and fourth battery cells 412 and 413 are not electricallyconnected to each other so as to be divided and separated from eachother. According to the arrangement relationship between these left leadplates, the first and second left lead plates 461 and 462 adjacent toeach other serve as the lead plates 45 of which the electricalpotentials are different from each other. Further, the second and thirdleft lead plates 462 and 463 are arranged and constructed to form aseparate configuration such that the fifth and sixth battery cells 414and 415 and the seventh and eighth battery cells 416 and 417 are notelectrically connected to each other so as to be divided and separatedfrom each other. According to the arrangement relationship between theseleft lead plates, the second and third left lead plates 462 and 463adjacent to each other serve as the lead plates 45 of which theelectrical potentials are different from each other. That is,individually, the left lead plates 46 (461, 462, and 463) are arrangedadjacent to each other along the direction where the electrodes 42 ofthe ten battery cells 41 disposed in parallel are adjacent to eachother, and the electrical potentials of the left lead plates 46 aredifferent from each other.

Moreover, as shown in FIG. 4, the right lead plates 47 are also formedof three plate-like terminals that are separated from each other. Thethree right lead plates 47 are denoted by reference numerals as a firstright lead plate 471, a second right lead plate 472, and a third rightlead plate 473 in this order from the front side. That is, as shown inFIG. 4, the first right lead plate 471 is mounted to extend between thefour right electrodes 42 of the first battery cell 410, the secondbattery cell 411, the third battery cell 412, and the fourth batterycell 413 among ten electrodes 42 that are formed at the right ends ofthe battery cells 41. Further, the second right lead plate 472 ismounted to extend between the four right electrodes 42 of the fifthbattery cell 414, the sixth battery cell 415, the seventh battery cell416, and the eighth battery cell 417. Furthermore, the third right leadplate 473 is mounted to extend between the two right electrodes 42 ofthe ninth battery cell 418 and the tenth battery cell 419.

Meanwhile, conversely, as shown in FIG. 4, the first and second rightlead plates 471 and 472 are arranged and constructed to form a separateconfiguration such that the third and fourth battery cells 412 and 413and the fifth and sixth battery cells 414 and 415 are not electricallyconnected to each other so as to be divided and separated from eachother. According to the arrangement relationship between these rightlead plates, the first and second right lead plates 471 and 472 adjacentto each other are formed of the lead plates 45 of which the electricalpotentials are different from each other. Further, the second and thirdright lead plates 472 and 473 are arranged and constructed to form aseparate configuration such that the seventh and eighth battery cells416 and 417 and the ninth and tenth battery cells 418 and 419 are notelectrically connected to each other so as to be divided and separatedfrom each other. According to the arrangement relationship between theseright lead plates, the second and third right lead plates 472 and 473adjacent to each other are formed of the lead plates 45 of which theelectrical potentials are different from each other. That is,individually, the right lead plates 47 (471, 472, and 473) are alsoarranged adjacent to each other along the direction where the electrodes42 of the ten battery cells 41 disposed in parallel are adjacent to eachother, and the electrical potentials of the right lead plates 47 aredifferent from each other.

Next, the housing case 20 in which the above-mentioned battery pack body40 is disposed will be described.

The housing case 20 has a function as an outer cover case of the batterypack 10 and also has a function as a housing in which the battery packbody 40 is disposed. The housing case 20 includes a box-shaped case body21 with an opened upper portion, and an upper cover member 31 thatcloses the opened upper portion of the case body 21 as an upper cover ofthe case body 21. The case body 21 and the upper cover member 31 arefastened to each other by screw members 39.

First, the upper cover member 31 of the housing case 20 will bedescribed.

The upper cover member 31 serves as a connection-side outer cover of thehousing case 20 when the battery pack 10 is slid to be mounted. That is,the upper cover member 31 is formed to have a structure capable ofsliding to be mounted on the mounting target such as the tool body.Specifically, slide guide portions 32, which guide the slide mounting,are formed at the middle portion of the upper cover member 31. Further,the upper cover member 31 is provided with connection openings 33 thatallow the terminals of the mounting target to be connected to theabove-mentioned connection terminal portions 53 (the connection controlboard 51). The upper cover member 31 is provided with a hook-exposureopening 34 through which the hook-type structure 56 (the male hookmechanism 55) to be locked to the mounting target is exposed to theoutside. The upper cover member 31 is provided with an air vent opening35 through which air is sent to cool the inside of the housing case 20.The air vent opening 35 includes a first air vent opening 36 throughwhich cooling air is sent into the housing case 20 and second air ventopenings 37 through which the cooling air sent into the housing case 20is discharged to the outside of the housing case 20 after cooling thebattery cells 41. Meanwhile, the slide guide portions 32, the connectionopenings 33, and the like are formed to have shapes that cope with theslide mounting of the battery pack 10.

Next, the case body 21 of the housing case 20 will be described.

A cross-sectional view of FIG. 5 shows the cross-section of the batterypack 10 of FIG. 2 taken along line V-V. A cross-sectional view of FIG. 6is an enlarged cross-sectional view of a portion (a portion that ismarked with a circle shown in FIG. 5 by a chain line) of the case body21 of FIG. 5 where a drain hole 25 is disposed. A top view of FIG. 7shows the case body 21 that is seen from the top so that the inside ofthe case body 21 is seen. A top view of FIG. 8 enlarges and shows theportion (the portion that is marked with a circle shown in FIG. 5 by achain line) of the case body 21 of FIG. 7 where the drain hole 25 isdisposed. Meanwhile, in FIGS. 5 and 6, the battery pack 10 is placed ona placement surface F that forms a horizontal surface.

As also shown in FIG. 1, the case body 21 is formed in the shape of abox which is surrounded by one bottom wall portion 211 and four sidewall portions 212 and of which the upper portion is opened so that theabove-mentioned battery pack body 40 can be installed. Meanwhile, thebottom wall portion 211 of the case body 21 corresponds to a bottomportion according to the invention. As shown in FIG. 5, the case body 21is formed so that the above-mentioned battery cells 41 can be installedin the case body 21. An outer surface 221 of the bottom wall portion 211of the case body 21 is formed substantially flush as shown in FIG. 5,while ribs 23, which appropriately have concave and convex shapes, areprovided on an inner surface 222 of the bottom wall portion. The ribs 23have an appropriately uneven shape, and are formed so as to protrudetoward the inside of the case body 21. The ribs 23 are formed of threekinds of ribs, that is, support ribs 231, air guide ribs 232, andforeign material-introduction restricting ribs 233. As shown in FIGS. 5and 6, the support ribs 231 mainly function as ribs that support thebattery cells 41 to be installed in order to stabilize the installationstate of the battery cells 41 that are to be installed in the case body21. For this reason, the support ribs 231 are formed in the shapes ofconcave curved surfaces corresponding to the curved surface shapes ofthe outer peripheries of the battery cells 41 to be installed.Meanwhile, the support ribs 231 also contribute to improve the strengthof the strength of the case body 21. Further, as shown in FIG. 6, theair guide ribs 232 function as guides for guiding cooling air whencooling air is sent to the second air vent openings 37 from the firstair vent opening 36 for cooling the battery cells 41. For this purpose,the shapes of the air guide ribs 232 are selected so that air sent intothe case body 21 can efficiently cool the battery cells 41. Meanwhile,the air guide ribs 232 also have the same function as theabove-mentioned support ribs 231, that is, a function as ribs, whichsupport the battery cells 41 to be installed, and the like. The foreignmaterial-introduction restricting ribs 233 will be described after thedescription of the drain holes 25 that will be described next.

As shown in FIGS. 3 and 4, the case body 21 is provided with drain holes25 having a function of discharging the water, which has been introducedinto the housing case 20, to the outside of the housing case 20.Meanwhile, the drain holes 25 are included in a drainage function-shapeportion according to the invention. The drain holes 25 are disposed atthe bottom wall portion 211, which forms the bottom portion of thehousing case 20, so that the inside and the outside of the housing case20 communicate with each other. The arrangement positions of the drainholes 25 are set to be present between the lead plates 45, which areconnected to the electrodes 42 of the above-mentioned battery cells 41,at the bottom wall portion 211 of the housing case 20. For this reason,as understood from the comparison between FIG. 2 and FIGS. 3 and 4, thedrain holes 25 are disposed so as to be present between the four of therespective lead plates 45.

Individually and specifically, at the left portion of the bottom wallportion 211 of the housing case 20, a first drain hole 251 is disposedbetween the above-mentioned first and second left lead plates 461 and462; a second drain hole 252 is disposed between the above-mentionedsecond and third left lead plates 462 and 463. In contrast, at the rightportion of the bottom wall portion 211 of the housing case 20, a thirddrain hole 253 is disposed between the above-mentioned first and secondright lead plates 471 and 472; a fourth drain hole 254 is disposedbetween the above-mentioned second and third right lead plates 472 and473.

That is, there are a total of four drain holes 25 disposed on the casebody 21. There are a total of six lead plates 45, which means there aretwo fewer drain holes 25 than head plates 45. There are ten totalbattery cells 41, which means there are four fewer drain holes 25 thanbattery cells 41. Meanwhile, as shown in FIG. 8, the shapes of thesedrain holes 25 are set to have a circular shape in top view, and thediameters of the drain holes 25 are set to 2.5 mm that is not anexcessively large diameter.

In other words, the first drain hole 251 drains water that is presentbetween the first and second left lead plates 461 and 462, and thesecond drain hole 252 drains water that is present between the secondand third left lead plates 462 and 463. Further, the third drain hole253 drains water that is present between the first and second right leadplates 471 and 472, and the fourth drain hole 254 drains water that ispresent between the second and third right lead plates 472 and 473.

Here, the respective drain holes 25 (251, 252, 253, and 254) are set asdescribed below and are disposed at the bottom wall portion 211 of thehousing case 20. The drain hole 25 will be described with reference toFIGS. 6 and 8 that are enlarged views. Meanwhile, in the drain hole 25,an opening end edge of the drain hole 25, which is disposed at the outerportion of the housing case 20, is set as an outer end edge 261; anopening end edge of the drain hole 25, which is disposed at the innerportion of the housing case 20, is set as an inner end edge 262. Thatis, as shown in FIG. 6, the shape of the outer end edge 261 of the drainhole 25 (251) is set so that the outer end edge 261 slightly risestoward the inside of the housing case 20 as compared with a supportlower surface 201 of the housing case 20 that corresponds to theperipheral portion of the outer end edge 261. For this reason, aclearance C is formed between the outer end edge 261 and the placementsurface F with which the support lower surface 201 of the housing case20 corresponding to the peripheral portion of the outer end edge 261comes into contact.

Further, the foreign material-introduction restricting ribs 233 areprovided in the housing case 20. That is, as shown in FIG. 6, theforeign material-introduction restricting rib 233 is provided at aposition, which is spaced upward from the inner end edge 262 of thedrain hole 25, on a portion that is positioned above the inner end edge262 of the above-mentioned drain hole 25. That is, the foreignmaterial-introduction restricting rib 233 is provided so as to be spacedupward from the inner end edge 262 of the drain hole 25 while the openedstate of the drain hole 25 is maintained. Furthermore, as shown in FIG.8, the foreign material-introduction regulating rib 233 is provided inthe housing case 20 so as to cross the shape of the opening of the drainhole 25.

According to the battery pack 10 having the above-mentioned structure,it is possible to obtain the following functions and effects.

That is, according to the above-mentioned battery pack 10, since thearrangement positions of the drain holes 25 are set to be presentbetween the lead plates 45 that are connected to the electrodes 42 ofthe battery cells 41, it is possible to discharge the water, which ispresent between the lead plates 45, to the outside of the housing case20 from the inside of the housing case 20. Accordingly, since it ispossible to drain water so that the water present at least between thelead plates 45 is removed, it is possible to prevent the electricalconnection between the lead plates 45, which may be caused when the leadplates 45 soak in water. That is, even though appropriate ribs 23, suchas the support ribs 231 and the air guide ribs 232, are formed in thehousing case 20 so as to support the battery cells 41, it is possible toprevent the electrical connection between the lead plates 45, which maybe caused when at least the lead plates 45 soak in the water, whileallowing a puddle to be formed by the ribs 23. Accordingly, it ispossible to prevent the unintended electrical connection between thelead plates 45, which may be caused when the lead plates 45 soak inwater. That is, it is possible to efficiently drain the water, which hasbeen introduced into the housing case 20, to the outside of the housingcase 20 so that the leakage of the electricity charged in the batterycells 41 is prevented. Further, since positions of the drain holes 25 tobe disposed is suppressed to be minimum positions that can prevent theunintended electrical connection between the lead plates 45, it ispossible to make the number of holes for drainage be as small aspossible.

Furthermore, according to the above-mentioned battery pack 10, since thelead plates 45 between which the arrangement positions of the drainholes 25 are set are the lead plates 45 that are adjacent to each otherand have different electrical potentials, it is possible to set aposition, where water is drained so as to be removed, between the leadplates 45 that are adjacent to each other and have different electricalpotentials. Accordingly, since it is possible to set a position, wherewater is to be drained so as to be removed and an insulation state is tobe maintained, to a position where a short circuit between the leadplates 45 easily occurs, it is possible to more reliably prevent a shortcircuit that is caused when the lead plates 45 soak in water.

Moreover, according to the above-mentioned battery pack 10, the shape ofthe outer end edge 261 of the drain hole 25, which is disposed at theouter portion of the housing case 20, is set so that the outer end edge261 rises toward the inside of the housing case 20 as compared with thesupport lower surface 201 corresponding to at least the peripheralportion of the outer end edge 261. Accordingly, even when the batterypack 10 mounted on the tool body (not shown) is placed on a desk or theground such that the support lower surface 201, which is the bottomportion of the battery pack 10, comes into contact with the placementsurface F, the outer end edge 261 of the drain hole 25 is positionedabove the placement surface F by the clearance C. Therefore, it ispossible to prevent the drain hole 25 from being closed by the placementsurface F, and hence it is possible to discharge the water, which isintroduced into the housing case 20, to the outside of the housing case20 from the drain hole 25. In addition, since it is possible to form thesmall clearance C between the outer end edge 261 of the drain hole 25and the placement surface F, it is possible to easily guide the water,which is present in the housing case 20, to the outside of the housingcase 20 by the surface tension of the water that has been introducedinto the clearance C. Accordingly, it is possible to efficiently drainthe water, which has been introduced into the housing case 20, to theoutside of the housing case 20.

Further, according to the above-mentioned battery pack 10, the foreignmaterial-introduction restriction rib 233, which crosses the shape ofthe opening of the drain hole 25 in the housing case 20, is provided inthe housing case 20. Accordingly, even in the case of possibleintroduction of foreign materials into the housing case 20 from theoutside of the housing case 20 through the drain hole 25, it is possibleto hinder the introduction of the foreign materials by the foreignmaterial-introduction restricting rib 233. Therefore, it is possible tomaintain the inside of the housing case 20 clean.

Next, two modifications of the battery pack 10 of the first embodimentwill be described with reference to FIGS. 9 and 10. FIG. 9 is across-sectional view of a battery pack 10A showing a modification wheredrain passages 27 are provided. FIG. 10 is an enlarged top view of adrain hole 25A showing a modification where drawing grooves 28 areprovided.

The two modifications shown in FIGS. 9 and 10 are examples where thearrangement positions of the drain holes 25 are set to be presentbetween the lead plates 45 as described above. The two modifications areexamples where a flow guide device or a draw guide mean device isprovided at a position different from the position between the leadplates 45 where the arrangement positions of the drain holes 25 are set.

Meanwhile, the flow guide device and the draw guide device are includedin the drainage function-shape portion according to the invention. Theflow guide device and the draw guide device are formed by forming ashape, which has a function of discharging the water having beenintroduced into the housing case 20 to the outside of the housing case20, on the housing case 20.

These modifications are different from the above-mentioned battery pack10 in that the structure of the drain passages 27 as the flow guidedevice or the structure of the drawing grooves 28 as the draw guidedevice is provided. For this reason, this battery pack 10 configurationis the same as the above-mentioned battery pack 10 except for thedifferent drain passage 27. Accordingly, portions having the samestructure as the structure of the portions of the above-mentionedbattery pack 10 are denoted by the same reference numerals as thereference numerals used in the above-mentioned battery pack 10 or thesame reference numerals that have “A” at the ends thereof and thedescription thereof will be omitted.

Meanwhile, in the modifications that will be described below, thearrangement positions of the drain holes 25 are set to be presentbetween the lead plates 45 as in the above-mentioned battery pack 10. Incontrast, the structure of the drain passages 27 as the flow guidedevice or the structure of the drawing grooves 28 as the draw guidedevice is set at a position different from the position between the leadplates 45.

First, a modification where the drain passages 27 are provided in thebattery pack 10A will be described. The battery pack 10A shown in FIG. 9is provided with the drain passages 27 as the flow guide device. Thedrain passages 27 serve to guide the flow of water so that water flowstoward the drain holes 25. That is, the drain passages 27 are formed ona bottom surface 223 of the bottom wall portion 211 of the case body 21that forms the inner surface 222 of the housing case 20. The drainpassage 27 is formed so that the bottom surface 223 is inclined downwardtoward the drain hole 25. Specifically, on the bottom surface 223 thatis positioned below the second left lead plate 462, a front half of thedrain passage is formed as a first drain passage 271 inclined downwardtoward the first drain hole 251; a rear half thereof is formed as asecond drain passage 272 inclined downward toward the second drain hole252. That is, the bottom surface 223, which is positioned below thesecond left lead plate 462, is formed in the shape of a mountain, ofwhich the bases extend forward and rearward from a portion positionedbelow the middle of the second left lead plate 462 as a peak. Further,on the bottom surface 223 that is positioned below the third left leadplate 463, a front half of the drain passage is formed as a third drainpassage 273 inclined downward toward the second drain hole 252. That is,the bottom surface 223, which is positioned below the third left leadplate 463, is formed in the shape of the half of a mountain, of whichthe base extends forward from a portion positioned below the middle ofthe third left lead plate 463 as a peak. Meanwhile, the bottom surface223, which forms the inner surface 222, of the bottom wall portion 211of the case body 21 is formed obliquely; the outer surface 221, whichcomes into contact with the above-mentioned placement surface F so as tobe supported, is formed to be flush.

According to the battery pack 10A of this modification, it is possibleto obtain the following functions and effects in addition to thefunctions and effects that are obtained by the above-mentioned batterypack 10. That is, according to the above-mentioned battery pack 10A,since the drain passages 27 as the flow guide device are formed so thatthe bottom surface 223 of the housing case 20 is inclined downwardtoward the drain holes 25, it is possible to make the water, which hasbeen introduced into the housing case 20, flow toward the drain holes 25by the inclined structure of the drain passages 27. Accordingly, it ispossible to improve the drainage performance of not only the vicinity ofthe drain holes 25 but also portions forming the drain passages 27, sothat it is possible to expand a range that is desired to improve thedrainage performance. Further, according to this battery pack 10A, it ispossible to guide the water, which is present in the peripheral portionof the drain holes 25, to the drain holes 25 by the drain passages 27 asthe flow guide device, while it is possible to completely remove thewater, which is present between these lead plates 45, by using thepresence of the drain holes 25. Accordingly, it is possible to reliablyprevent the unintended electrical connection between the lead plates 45.

Next, a modification where the drawing grooves 28 are provided at drainholes 25A will be described.

The drain hole 25A shown in FIG. 10 is provided with the drawing grooves28 as the draw guide device. The drawing grooves 28 serve to draw andguide water so that water is collected toward the drain hole 25A. Thatis, the drawing grooves 28 act so as to draw water toward the drain hole25. In other words, the drawing grooves 28 are formed in a concavegroove shape so as to radially extend on the inner surface 222 of thehousing case 20 from the inner end edge 262 of the drain hole 25.Specifically, five drawing grooves 28, which radially extend in aconcave groove shape, are formed in a peripheral portion, which is shownon the left side in the drawing, of the drain hole 25A. The five drawinggrooves 28 are appropriately cut into a surface of the peripheralportion so as to have a small depth and are formed at appropriateintervals from each other.

According to the drain hole 25A of this modification, it is possible toobtain the following functions and effects in addition to the functionsand effects that are obtained by the above-mentioned battery pack 10.That is, since the drawing grooves 28 as the draw guide device areformed in a concave groove shape so as to radially extend on the innersurface 222 of the housing case 20 from the inner end edge 262 of thedrain hole 25, the drawing grooves 28 can act so as to draw the water,which is present in the peripheral portion of the inner end edge 262,toward the drain hole 25. For this reason, it is possible to make thecomplete drainage of the water, which is present between the lead plates45, so as to affect to the peripheral portion of the drain hole 25A.Accordingly, it is possible to more reliably prevent the electricalconnection between the lead plates, which may be caused when theabove-mentioned lead plates 45 soak in water. Further, with the batterypack provided with the drain holes 25A, it is possible to guide thewater, which is present in the peripheral portion of the drain holes 25,to the drain holes 25A by the drawing grooves 28 as the draw guidedevice and to completely remove the water, which is present betweenthese lead plates 45, by using the presence of the drain holes 25A.Accordingly, it is possible to reliably prevent the unintendedelectrical connection between the lead plates 45.

Second Embodiment

Next, the second embodiment, which embodies the battery pack accordingto the invention, will be described with reference to FIGS. 11 and 12.Here, a perspective view of FIG. 11 is a perspective view of a case body21B that is viewed in perspective so that the inside of the case body isseen. Further, a cross-sectional view of FIG. 12 is a cross-sectionalview of the case body 21B of FIG. 11 taken along line XII-XII.

That is, although the entire view is not shown, the battery pack of thesecond embodiment is different from the battery pack 10 of theabove-mentioned first embodiment only in the structure of the case body21. That is, in the battery pack of the second embodiment, a part of thestructure of a drain passage 27B as a flow guide device is set to bepresent between the lead plates 45; a drain hole 25B is set to aposition different from the position between the lead plates 45 unlikein the modification of the above-mentioned first embodiment.

The second embodiment is different from the above-mentioned battery pack10 in the arrangement structure of the drain passage 27B used as a flowguide device and in the arrangement structure of the drain hole 25B. Forthis reason, since the structure, except for these different structures,is the same as that of the above-mentioned battery pack 10, the samereference numerals as the reference numerals described in theabove-mentioned battery pack 10 are given in the drawings and thedescription of the same structure will be omitted.

That is, as shown in FIGS. 11 and 12, the bottom wall portion 211 of thecase body 21B corresponding to the bottom portion according to theinvention is provided with the drain hole 25B. As shown in FIGS. 11 and12, the drain hole 25B is formed substantially at the center of thebottom wall portion 211. Like the above-mentioned drain hole 25, thedrain hole 25B has a function of discharging the water, which has beenintroduced into the housing case 20, to the outside of the housing case20. However, while the arrangement position of the drain hole 25 of thebattery pack 10 of the above-mentioned first embodiment has been set tobe present between the lead plates 45, the arrangement position of thedrain hole 25B of the battery pack of the second embodiment is set tothe middle of the bottom wall portion 211 with respect to a left andright direction. Like the above-mentioned drain hole 25, the drain hole25B is disposed so that the inside and the outside of the housing case20 communicate with each other. In contrast, the drain passage 27B isformed on the bottom surface 223 of the bottom wall portion 211 of thecase body 21, which forms the inner surface 222 of the housing case 20,so as to extend in the left and right direction of the case body 21.Specifically, the drain passage 27B is formed in the shape of a groovethat is inclined downward toward the drain hole 25B, which is formedsubstantially at the center of the bottom wall portion 211, from aportion (a portion that is marked with a circle shown in FIGS. 11 and 12by a phantom line), where the first drain hole 251 of theabove-mentioned first embodiment is disposed, as a peak. That is, thehighest portion of the drain passage 27B is set to be positioned betweenthe above-mentioned first and second left lead plates 461 and 462(corresponding to a position where the first drain hole 251 of the firstembodiment is disposed). Further, the lowest portion of the drainpassage 27B is a portion where the drain hole 25B is disposed.

According to the battery pack of the second embodiment, the arrangementposition of the drain hole 25B is set substantially to the center of thebottom wall portion 211 and a peak portion of the drain passage 27B isset to be positioned between the first and second left lead plates 461and 462 (corresponding to the position where the first drain hole 251 ofthe first embodiment is disposed). Accordingly, it is possible to drainthe water, which is present between the lead plates 45, to the outsideof the housing case 20 from the inside of the housing case 20 and to setthe arrangement position of the drain hole 25B substantially to thecenter of the bottom portion of the housing case 20 according to thedesign of the battery pack. Therefore, it is possible to increase thedegree of freedom of the arrangement position of the drain hole 25B, sothat it is also possible to increase the degree of freedom in the designof the battery pack.

Meanwhile, the battery pack according to the invention is not limited tothe above-mentioned embodiments and portions may be appropriatelychanged as will be described below.

That is, in the above-mentioned embodiments, the inclined structure ofthe drain passages 27 as the flow guide device and the drawing structureof the drawing grooves 28 have been described as an example of thedrainage function-shape portion. However, the drainage function-shapeportion according to the invention is not limited to such an example,and may be of any portion as long as it is formed to have a function ofdischarging the water, which has been introduced into the housing case,to the outside of the housing case while including a drain hole thatmakes the inside and outside of the housing case 20 communicate witheach other. For example, various shapes, such as those having anappropriate inclination, appropriate grooves, or appropriate steps, maybe selected. Further, the drain holes 25, which makes the inside andoutside of the housing case communicate with each other as describedabove, may form the drainage function-shape portion according to theinvention alone.

Second Example

Next, third and fourth embodiments, which are embodied in a secondexample shown in FIGS. 13 to 21, will be described.

Third Embodiment

The third embodiment, which embodies the battery pack according to theinvention, will be described below with reference to FIGS. 13 to 17.

FIG. 13 shows the appearance of a battery pack 110, which is the thirdembodiment embodied in the second example, in perspective. FIG. 14 showsthe battery pack 110 that is seen from above. FIG. 15 shows thecross-section of the internal structure of the battery pack 110 takenalong line XV-XV in FIG. 14. FIG. 16 shows the cross-section of theinternal structure of the battery pack 110 taken along line XVI-XVI inFIG. 14. Meanwhile, in the following description, the electricalconnection side of the battery pack 110 is defined as the upper side andthe slide mounting direction of the battery pack 110 is defined as afront side.

The battery pack 110 shown in FIGS. 13 to 16 is adapted to be detachablymounted by sliding onto a tool body of an electric tool that is typifiedby, for example, an electric screwdriver. The battery pack 110 serves asa drive power source of the tool body on which the battery pack 110 hasbeen mounted. That is, when the charge amount of the battery pack 110 isreduced, the battery pack 110 is removed from the tool body and chargedby a dedicated external charger. After being completely charged by thededicated charger, the battery pack 110 is mounted on the tool body andfunctions as a drive power source. Meanwhile, the battery pack 110 isadapted to be mounted (slid to be mounted) on a tool body (not shown) ora dedicated charger (not shown) by sliding when the battery pack 110 isto be mounted on the tool body or the dedicated charger.

As shown in FIG. 15, etc., the battery pack 110 generally includes ahousing case 111 and an internal installation body 121.

The housing case 111 has a function as an outer cover of the batterypack 110 and a function as a housing in which the internal installationbody 121 is disposed. The housing case 111 includes a box-shaped casebody 112 of which an upper portion is opened, and an upper cover member116 that closes the opened upper portion of the case body 112 as anupper cover of the case body 112. The case body 112 is configured sothat the internal installation body 121 can be disposed in thebox-shaped inner portion of the case body. The upper cover member 116 ismounted so as to close the opened upper portion of the case body 112where the internal installation body 121 is disposed in the box-shapedinner portion, and is fastened by fastening screws 119 as shown in FIGS.13 and 14. Accordingly, the housing case 111 is formed of a housing inwhich the internal installation body 121 is disposed. Meanwhile, anopening shape is formed on the housing case 111 for communicating withthe inside of the housing case 111 from the outside of the housing case111 in order to arrange electrical connection portions 134 and a malehook mechanism 140 that will be described in detail below.

The internal installation body 121 has a function as a power source ofthe battery pack 110. That is, as shown in FIGS. 15 and 16, the internalinstallation body 121 includes a plurality of battery cells 122 and acontrol board 126 that is electrically connected to the plurality ofbattery cells 122. The battery cells 122 are formed of battery cells,which can be charged, so that the battery pack 110 functions as a drivepower source of a tool body. The plurality of battery cells 122 aredisposed within the above-mentioned housing case 111, and areelectrically connected to the control board 126. The control board 126appropriately performs controls when the battery cells 122 are chargedor discharged. Meanwhile, the control board 126 is electricallyconnected to a connection terminal 1361 of a positive connection portion1341, a connection terminal 1362 of a negative connection portion 1342,and a connection terminal 1363 of a control connection portion 1343 thatare shown in FIG. 14 and will be described below.

Incidentally, a slide mounting portion 130, which is to be mounted on atool body (not shown) or a dedicated charger (not shown), is provided onthe upper surface of the above-mentioned housing case 111. The slidemounting portion 130 has a function of allowing the battery pack 110 toslide to be mounted on the tool body (not shown) or the dedicatedcharger (not shown). For this reason, the slide mounting portion 130 hasa function of guiding the slide mounting of the battery pack 110, and afunction as an electrical connection portion for allowing the electricalconnection with the battery pack 110 that is mounted by sliding. Thatis, the slide mounting portion 130 includes the slide guide portions 131that guide the slide mounting of the battery pack 110, and theelectrical connection portions 134 that electrically connect the batterypack 110.

The slide guide portions 131 are formed in male guide shapes thatprotrude in a left-and-right width direction in the shape of an outerflange and extend in a front and rear direction. The slide guideportions 131 can be fitted to female guide shapes, which are formed onthe tool body (not shown) or the dedicated charger (not shown), in theslide direction. For this reason, the slide guide portions 131 areformed in the shapes of outer flanges, which appropriately protrude inthe left-and-right width direction, so as to make a pair in theleft-and-right width direction on an upper surface 117 of the batterypack 110. Meanwhile, the front side of the battery pack 110, which isdefined in the drawings as described above, conforms to the slidemounting direction and the rear side of the battery pack 110. The rearside of the battery pack is defined in the drawings and conforms to aremoval direction.

The electrical connection portions 134 are provided on the rear side ofthe above-mentioned slide guide portions 131. The electrical connectionportions 134 are portions that are electrically connected to theconnection terminals provided on the tool body when the battery pack 110is slid to be mounted on the tool body as a mounting target. For thisreason, the electrical connection portions 134 are formed of the threeconnection portions. That is, the positive and negative connectionportions 1341 and 1342 that are connection portions for the charge ordischarge of electric power, while the control connection portion 1343is a connection portion to be connected to the above-mentioned controlboard 126.

These three electrical connection portions 134 (the positive connectionportion 1341, the negative connection portion 1342, and the controlconnection portion 1343) generally include terminal receiving grooves135 and battery-side connection terminals 136, which are individuallyand specifically configured as described below. Meanwhile, since thepositive and negative connection portions 1341 and 1342 aresymmetrically formed so as to make a pair, the positive connectionportion 1341 will be described in the following description, and thesame description will be applied to the negative connection portion1342.

That is, the positive connection portion 1341 (the negative connectionportion 1342) includes a receiving groove 1351 (a receiving groove 1352)as the terminal receiving groove 135 and a connection terminal 1361 (aconnection terminal 1362) as the battery-side connection terminal 136.The receiving groove 1351 is a concave groove that extends in the frontand rear direction of the battery pack 110. For example, a toolbody-side connection terminal (not shown) for supplying electric poweris slid to be fitted into the receiving groove 1351. The connectionterminal 1361 is disposed in the receiving groove 1351. The connectionterminal 1361 is electrically connected to the tool body-side connectionterminal (not shown) that is slid to be fitted into the concave grooveof above-mentioned receiving groove 1351. The connection terminal 1361is formed by leaf spring-type metal terminals that are disposed so as toface each other as shown in FIGS. 14 and 16.

The control connection portion 1343 is provided between theabove-mentioned positive and negative connection portions 1341 and 1342.The control connection portion 1343 includes a receiving groove 1353 asthe terminal receiving groove 135 and a connection terminal 1363 as thebattery-side connection terminal 136. The receiving groove 1353 is aconcave groove extending in the front and rear direction of the batterypack 110. For example, a tool body-side control connection terminal (notshown) is slid to be fitted into the receiving groove 1353. Meanwhile,the length of the receiving groove 1353 is set to be shorter than thelength of the receiving groove 1351 (the receiving groove 1352) of theabove-mentioned positive connection portion 1341 (the negativeconnection portion 1342). The connection terminal 1363, which has thesame structure as the structure of the connection terminal 1361 (theconnection terminal 1362) of the above-mentioned positive connectionportion 1341 (the negative connection portion 1342), is disposed in thereceiving groove 1353.

Meanwhile, the connection terminal 1361 of the positive connectionportion 1341, the connection terminal 1362 of the negative connectionportion 1342, and the connection terminal 1363 of the control connectionportion 1343 are electrically connected to the above-mentioned controlboard 126. For this purpose, opening shapes, which communicate with theinside of the housing case 111 from the outside of the housing case 111for allowing connection to the control board 126, are formed at aportion where the connection terminal 1361 (the positive connectionportion 1341) is arranged, an portion where the connection terminal 1362(the negative connection portion 1342) is arranged, and a portion wherethe connection terminal 1363 (the control connection portion 1343) isarranged. The communicating opening shapes correspond to a communicationopening according to the invention.

For this reason, the peripheral portion of the portion where theconnection terminal 1361 (the positive connection portion 1341) isarranged, the peripheral portion where the connection terminal 1362 (thenegative connection portion 1342) is arranged, and the peripheralportion where the connection terminal 1363 (the control connectionportion 1343) is arranged are portions that correspond to the vicinityof the communication opening according to the invention. Specifically,portions on the front side of the electrical connection portions 134,which include these connection terminals 1361, 1362, and 1363, are setas the peripheral portions of the arrangement portions of theseconnection terminals 1361, 1362, and 1363 and are portions thatcorrespond to the vicinity of the communication opening according to theinvention. Here, portions on the front side of the electrical connectionportions 134 including the connection terminals 1361, 1362, and 1363 arepositioned between the slide guide portions 131. They also serve asupper surface portions of the upper cover member 116. Additionally, theyserve as the upper surface of the housing case 111. Finally, they alsoserve as the upper surface 117 of the battery pack 110 as a whole.

FIG. 17 shows the upper surface 117 of the battery pack 110 in anenlarged version of that shown in FIG. 16 for easy understanding of theupper surface 117 of the battery pack 110 positioned on the front sideof the electrical connection portions 134 having the connectionterminals 1361, 1362, and 1363. Meanwhile, the battery pack 110 shown inFIG. 17 is shown as the upper surface 117 of the battery pack 110 whenthe battery pack 110 is placed on the horizontal surface. Further, inFIG. 17, a horizontal line is shown for the upper surface 117 for easyunderstanding of the inclined structure of the upper surface 117 of thebattery pack 110.

As shown in FIG. 17, the upper surface 117 of the battery pack 110 isformed to have an inclined structure (the shape of an inclined flatsurface). The upper surface 117 of the battery pack 110 has the shape ofa substantially flat surface, and has an angle of inclination such thatit is inclined downward with respect to the battery pack 110 toward thefront side of the battery pack 110. In other words, the upper surface117 of the battery pack 110 is formed in the shape of a flat surfacethat is inclined upward toward the electrical connection portions 134positioned at the rear portion of the battery pack 110.

That is, since the upper surface 117 of the battery pack 110 has aninclined structure having the shape of a flat surface that is inclineddownward with respect to the battery pack 110 toward the front side ofthe battery pack 110, the upper surface 117 of the battery pack 110constitutes a water-introduction restricting portion according to theinvention. That is, when water is put on the upper surface 117 of thebattery pack 110 such as when water is splashed on the battery pack 110,the water present on the upper surface 117 of the battery pack 110 doesnot flow toward the portions where the electrical connection portions134 are arranged (the portion where the connection terminal 1361 of thepositive connection portion 1341 is arranged, the portion where theconnection terminal 1362 of the negative connection portion 1342 isarranged, and the portion where the connection terminal 1363 of thecontrol connection portion 1343 is arranged) on the upper surface 117 ofthe battery pack 110 but flows toward the front side of the battery pack110 that is opposite to the portions where the electrical connectionportions 134 are arranged. In other words, water present on the uppersurface 117 of the battery pack 110 flows in the direction away from theportions where the electrical connection portions 134 are arranged (theportion where the connection terminal 1361 of the positive connectionportion 1341 is arranged, the portion where the connection terminal 1362of the negative connection portion 1342 is arranged, and the portionwhere the connection terminal 1363 of the control connection portion1343 is arranged), so that the introduction of water into the portionswhere the electrical connection portions 134 (the connection terminals1361, 1362, and 1363) are arranged is restricted.

Incidentally, as shown in FIG. 17, a stepped portion 137 is formed at aboundary portion between the above-mentioned electrical connectionportion 134 (the positive connection portion 1341) and the upper surface117 of the battery pack 110 positioned on the front side of theelectrical connection portion 134 (the positive connection portion1341). The stepped portion 137 is formed by making the front end portionof the electrical connection portion 134 (the positive connectionportion 1341), which is set at the boundary portion, to have a shapeprotruding toward the upper side of the battery pack 110.

Meanwhile, since FIG. 17 is an enlarged view of FIG. 16, the steppedportion 137 formed at the front end portion of the positive connectionportion 1341 as the electrical connection portions 134 has beendescribed. However, the same stepped portions 137 as the stepped portion137 formed at the front end portion of the positive connection portion1341 are also formed at the respective front end portions of thenegative connection portion 1342 and the control connection portion 1343as the electrical connection portions 134.

On the other hand, a male hook mechanism 140, which is fitted to afemale hook portion (not shown) formed on the tool body when the batterypack is mounted on the above-mentioned tool body (mounting target), isformed at the rear portion of the above-mentioned battery pack 110. Themale hook mechanism 140 corresponds to a male hook portion according tothe invention. The male hook mechanism 140 is disposed so as to bereceived in a receiving space (a mechanism receiving space 118) that isformed between the above-mentioned housing case 111 and the internalinstallation body 121. A male hook mechanism 140 disposed in themechanism receiving space 118 will be explained below.

As shown in FIGS. 15 and 16, the male hook mechanism 140 includes a basemember 141, a male hook body 145, and a biasing coil spring 149. Asshown in FIG. 15, the base member 141 is fixed to the housing case 111by a screw member 142, so that the base member 141 is disposed in theabove-mentioned mechanism receiving space 118. The base member 141 has astructure that isolates the above-mentioned housing case 111 and theinternal installation body 121 from each other. That is, although notspecifically shown, the base member 141 is formed so that substantiallythe entire peripheral edge of the base member comes into contact withthe inner surface of the housing case 111. Thus, since substantially theentire peripheral edge of the base member comes into contact with thehousing case 111 as described above, the base member 141 may isolate thehousing case 111 and the internal installation body 121 from each other.For this reason, the inside of the base member 141 is not seen in FIG.16 that is a cross-sectional view of the battery pack 110 of FIG. 14taken along line XVI-XVI.

The male hook body 145 is disposed between the above-mentioned basemember 141 and the housing case 111. The male hook body 145 is a memberthat moves up and down relative to the base member 141 and the housingcase 111. For this reason, as shown in FIG. 15, the male hook body 145is formed so as to extend in the up and down direction in the housingcase 111 while being bent along the upper and rear surfaces of thehousing case 111. The male hook body 145 generally includes a biasingguide portion 146, an operation portion 147, and a hook portion 148 inorder from the lower side to the upper side shown in FIG. 15.

The biasing guide portion 146 forms the lower portion of the male hookbody 145, and comes into contact with the upper end of the biasing coilspring 149. Further, the biasing guide portion 146 is positioned betweenthe above-mentioned base member 141 and the housing case 111, so thatthe movement of the biasing guide portion 146 in the front and reardirection and the left and right direction is restricted. For thisreason, the biasing guide portion 146 has a function of guiding themovement of the male hook body 145 in the up and down direction whilereceiving a biasing force of the biasing coil spring 149. In contrast,the operation portion 147 and the hook portion 148 are formed so as tobe exposed to the outside. The operation portion 147 is formed in themiddle portion of the male hook body 145, and is formed in anappropriate concave shape that allows an operation finger of a user tobe caught as also shown in FIG. 13. The operation portion 147 is adaptedto be exposed to the outside through an operation portion exposurewindow 1111 that is formed at the rear portion of the housing case 111.The hook portion 148 is formed at the upper end of the male hook body145, and is formed in the shape of a male hook protruding upward as alsoshown in FIG. 13. The hook portion 148 is adapted to be exposed to theoutside through a hook portion exposure window 1112 that is formed atthe upper portion of the housing case 111. The hook portion 148 isformed in the shape of a male hook having an appropriate tapered shapeso as to be capable of being fitted to a female hook portion (notshown), which is provided on the tool body or the dedicated charger,according to the slide mounting of the battery pack 110.

For this purpose, the operation portion exposure window 1111 and thehook portion exposure window 1112, which have shapes of openingscommunicating with the inside of the housing case 111 from the outsideof the housing case 111, are formed at the housing case 111 in order toexpose the above-mentioned operation portion 147 and the hook portion148 to the outside. Specifically, the operation portion exposure window1111 is formed at the rear portion of the housing case 111 so that theabove-mentioned operation portion 147 can be operated up and down.Specifically, as shown in FIGS. 13 and 14, the operation portionexposure window 1111 is formed in the shape of a rectangular openingthat communicates with the inside of the housing case 111 from theoutside of the housing case 111. Further, as shown in FIGS. 13 and 14,the hook portion exposure window 1112 is formed at the upper portion ofthe housing case 111 so that the above-mentioned hook portion 148 canprotrude from and retreat into the hook portion exposure window 1112.The hook portion exposure window 1112 is formed in the shape of aU-shaped opening that communicates with the inside of the housing case111 from the outside of the housing case 111. Here, the operationportion exposure window 1111 and the hook portion exposure window 1112,which have the shapes of communication openings, correspond to thecommunication opening according to the invention. For this reason, theperipheral portions of the arrangement portions of the operation portionexposure window 1111 and the hook portion exposure window 1112correspond to the vicinity of the communication opening according to theinvention.

The biasing coil spring 149 is a coil spring that is widely used. Thelower end of the biasing coil spring 149 comes into contact with theinner surface of the base member 141, and the upper end of the biasingcoil spring 149 comes into contact with the lower portion of the malehook body 145. Accordingly, the biasing coil spring 149 biases the malehook body 145 upward. In this way, the male hook mechanism 140 in thenormal state urges the hook portion 148 of the male hook body 145 toprotrude from the hook portion exposure window 1112 by the biasing forceof the biasing coil spring 149. That is, the hook portion can be fittedto a female hook portion (not shown) that is provided on the tool body.On the other hand, when the operation portion 147 exposed to the outsidethrough the operation portion exposure window 1111 is moved downwardagainst the biasing force of the biasing coil spring 149, the hookportion 148 of the male hook body 145 protruding from the hook portionexposure window 1112 retreats. That is, it is possible to release thefitting between the hook portion 148 and the female hook portion (notshown).

Here, a stepped guide portion 150 is provided on the housing case 111 ata position on the upper side of the portion where the operation portionexposure window 1111 is arranged. The stepped guide portion 150 isformed in a convex shape that separates the water, which is present atthe peripheral portion of the arrangement portion of the hook portionexposure window 1112, from the hook portion exposure window 1112. Asshown in FIGS. 13 and 14, the stepped guide portion 150 is formed sothat the water, which is present on the outer surface of the housingcase 111, flows along the outer surface of the housing case 111 withoutreaching the hook portion exposure window 1112. Specifically, as shownin FIGS. 13 and 14, a stepped portion protruding outward in a shape of amountain with its upper side being convex, is formed at the steppedguide portion 150. The mountain-shaped stepped portion of the steppedguide portion 150 is formed so that a mountain-shaped peak portion(reference numeral 151) is positioned above the portion where theoperation portion exposure window 1111 is arranged and bothmountain-shaped bases (reference numeral 152) are positioned on bothleft and right sides of the portion where the operation portion exposurewindow 1111 is arranged. Meanwhile, the protruding height of the steppedguide portion 150, which is a difference in level, is set so as to bereduced from the mountain-shaped peak portion (reference numeral 151)toward both the mountain-shaped bases (reference numeral 152). Themountain-shaped stepped portion of the stepped guide portion 150 formsthe water-introduction restricting portion according to the invention.That is, the stepped guide portion 150 guides the movement of water soas to restrict the introduction of water into the operation portionexposure window 1111 when water is splashed on the battery pack 110 orthe like.

Meanwhile, since the above-mentioned base member 141 is configured so asto have a structure for isolating the housing case 111 and the internalinstallation body 121 from each other, it is possible to restrict theintrusion of the water, which is introduced into the housing case 111,into the internal installation body 121 by the base member 141 even inthe case that water has been introduced into the housing case 111 fromthe operation portion exposure window 1111 and the hook portion exposurewindow 1112.

According to the above-mentioned battery pack 110, it is possible toobtain the following functions and effects.

That is, according to the above-mentioned battery pack 110, openingshapes are formed in order to arrange the electrical connection portions134 and the male hook mechanism 140. Here, the stepped guide portion 150and the upper surface 117 of the above-mentioned battery pack 110 as thewater-introduction restricting portion, which is provided on the housingcase 111, act so as to restrict the introduction of the water, which issplashed from the outside, into the opening shapes. Accordingly, it ispossible to improve the waterproof property of the battery pack 110 byrestricting the intrusion of water into the housing case 111 from theoutside of the housing case 111.

Further, according to the above-mentioned battery pack 110, the inclinedstructure of the upper surface 117 of the battery pack 110 is providedon the front side of the portions where the battery-side connectionterminals 136 (the connection terminal 1361 of the positive connectionportion 1341, the connection terminal 1362 of the negative connectionportion 1342, and the connection terminal 1363 of the control connectionportion 1343) are arranged. Accordingly, it is possible to make thewater, which is present in the periphery of the portions where thebattery-side connection terminals 136 are arranged, to flow in thedirection away from the portions where the battery-side connectionterminals 136 are arranged, by the inclined structure. Therefore, sinceit is possible to separate the water, which is present on the uppersurface 117 of the battery pack 110, from the portions where thebattery-side connection terminals 136 are arranged, it is possible toimprove the waterproof property of the battery pack 110 by restrictingthe introduction of water into the housing case 111 from the outside ofthe housing case 111. Accordingly, it is possible to make the contactbetween water such as raindrops and the battery-side connectionterminals 136 more difficult.

Furthermore, according to the above-mentioned battery pack 110, sincethe water-introduction restricting portion is formed in the uneven shapethat isolates the water, which is present in the vicinity of thecommunication opening, from the communication opening, it is possible toseparate the water, which is present in the vicinity of thecommunication opening, from the communication opening. Accordingly, itis possible to restrict the introduction of water into the housing case111 from the outside of the housing case 111 by separating water fromthe communication opening, so that it is possible to improve thewaterproof property of the battery pack 110.

Moreover, according to the above-mentioned battery pack 110, the steppedguide portion 150 is provided on the housing case 111 on the upper sideof the operation portion exposure window 1111, which is a portion wherethe male hook mechanism 140 as a male hook portion is arranged. Due tothe stepped convex shape of the stepped guide portion 150, it ispossible to isolate the water, which is present in the periphery of theoperation portion exposure window 1111, from the operation portionexposure window 1111. Accordingly, it is possible to restrict theintroduction of water into the housing case 111 from the outside of thehousing case 111 by isolating water from the operation portion exposurewindow 1111, so that it is possible to improve the waterproof propertyof the battery pack 110.

Further, according to the above-mentioned battery pack 110, the steppedportions 137 are formed at the boundary portions between the electricalconnection portions 134 (the positive connection portion 1341, thenegative connection portion 1342, and the control connection portion1343) and the upper surface 117 of the battery pack 110 positioned onthe front side of the electrical connection portions 134. Accordingly,due to the stepped convex shape, it is possible to isolate the water,which is present in the periphery of the electrical connection portions134, from the electrical connection portions 134. Therefore, it ispossible to restrict the introduction of water into the housing case 111from the outside of the housing case 111 by isolating water from theelectrical connection portions 134, so that it is possible to improvethe waterproof property of the battery pack 110.

Fourth Embodiment

Next, the fourth embodiment, which embodies the battery pack accordingto the invention, will be described with reference to FIG. 18 and itssubsequent figures. Meanwhile, a battery pack 160 of the fourthembodiment is an embodiment where vent holes 171 and 181 are formed inthe structure of the battery pack 110 of the above-mentioned thirdembodiment. That is, the battery pack 160 of the fourth embodiment hassubstantially the same structure as the structure of the battery pack110 of the third embodiment. For this reason, the same portions of thebattery pack 160 of the fourth embodiment as the portions of the batterypack 110 of the above-mentioned third embodiment are denoted by thereference numerals having been used in the description of the batterypack 110 of the third embodiment, and the description thereof will beomitted. Meanwhile, the structure of a male hook mechanism 140A of thebattery pack 160 of the fourth embodiment is slightly different fromthat of the male hook mechanism 140 of the battery pack 110 of the thirdembodiment. That is, the male hook mechanism 140A of the fourthembodiment is different from the male hook mechanism 140 of the thirdembodiment in terms of the structure of the biasing coil spring 149, andother structures of the fourth embodiment are the same as those of thethird embodiment. For this reason, portions of the male hook mechanism140A of the fourth embodiment are denoted by reference numerals having“A” at the ends thereof, and the description thereof will be omitted.

FIG. 18 shows the appearance of the battery pack 160, which is thefourth embodiment, in perspective. FIG. 19 shows the battery pack 160that is seen from above. FIG. 20 shows the cross-section of the internalstructure of the battery pack 160 taken along line XX-XX in FIG. 19.FIG. 21 shows the cross-section of the internal structure of the batterypack 160 taken along line XXI-XXI in FIG. 19. Meanwhile, in thefollowing description, the electrical connection side of the batterypack 160 is defined as the upper side and the slide mounting directionof the battery pack 160 is defined as a front side.

Two vent holes 171 and 181 having appropriate opening shapes are formedin an upper surface 161 of the battery pack 160 shown in FIGS. 18 to 21.That is, reference numeral 171 denotes an intake-side vent hole. Theintake-side vent hole 171 is adapted to send cooling air, which has beensent from a dedicated charger or the like, toward an internalinstallation body 121 that is disposed in a housing case 111. Further,reference numeral 181 denotes an exhaust-side vent hole. Theexhaust-side vent hole 181 is adapted to discharge the cooling air thathas been sent to the internal installation body 121 and passed throughthe internal installation body 121. These vent holes 171 and 181 allowthe temperature of the internal installation body 121 (battery cells 122and a control board 126) to be lowered by cooling air and allow thetime, which is required until the battery pack 160 is fully charged, tobe shortened. In detail, during charging the battery pack 160 by adedicated charger, the temperature of the internal installation body 121(the battery cells 122 and the control board 126) rises due to thecharge of the battery pack 160. However, since the temperature of theinternal installation body 121 can be lowered by the cooling air sentfrom the vent holes 171 and 181, a charge effect is improved. As aresult, the time, which is required until the battery pack 160 is fullycharged, is shortened. That is, the cooling air, which is sent from adedicated charger or the like, is introduced into the housing case 111from the intake-side vent hole 171, cools the internal installation body121, and is discharged to the outside of the housing case 111 from theexhaust-side vent hole 181. Meanwhile, the exhaust-side vent hole 181 isformed in a shape that is merely opened, unlike the intake-side venthole 171 that will be described in detail below.

As shown in FIGS. 18 to 21, the two vent holes 171 and 181 are formed onthe upper surface 161 of the battery pack 160 at two portions, that is,rear and front portions of the battery pack 160. That is, theintake-side vent hole 171 is formed at the rear portion of the uppersurface 161 of the battery pack 160. The intake-side vent hole 171 isformed on the upper surface 161 of the battery pack 160 that is presentbetween the male hook mechanism 140A and the electrical connectionportions 134 (a positive connection portion 1341, a negative connectionportion 1342, and a control connection portion 1343). As also shown inFIG. 18, the intake-side vent hole 171 is formed in a shape of anopening in the upper surface 161 of the battery pack 160 so that air canbe introduced into the housing case 111 from the outside of the housingcase 111. For this reason, the intake-side vent hole 171 corresponds tothe communication opening according to the invention. Further, theperiphery of the portion where the intake-side vent hole 171 is arrangedcorresponds to the vicinity of the communication opening according tothe invention. Specifically, a peripheral edge 172 of the intake-sidevent hole 171 and a periphery 173 of the peripheral edge 172 are set asthe periphery of the portion where the intake-side vent hole 171 isarranged. Here, a first convex rib 175, which protrudes upward, isformed at the peripheral edge 172 of the intake-side vent hole 171. Thefirst convex rib 175 protrudes upward so as to be higher than theperiphery 173 of the intake-side vent hole 171 that forms the uppersurfaces of the electrical connection portions 134. For this reason, dueto the convex shape of the first convex rib 175, it is possible toisolate the water, which is present in the periphery 173 of the portionwhere the intake-side vent hole 171 is arranged, from the portion wherethe intake-side vent hole 171 is arranged. Accordingly, it is possibleto improve the waterproof property of the battery pack 160 byrestricting the intrusion of water into the housing case 111 from theintake-side vent hole 171.

Moreover, second convex ribs 177 are formed at the boundary portionsbetween the periphery 173 of the portion where the above-mentionedintake-side vent hole 171 is arranged and the above-mentioned electricalconnection portions 134 (the positive connection portion 1341, thenegative connection portion 1342, and the control connection portion1343). Like the above-mentioned first convex rib 175, the second convexribs 177 protrude upward so as to be higher than the periphery 173 ofthe intake-side vent hole 171 that forms the upper surfaces of theelectrical connection portions 134. For this reason, due to the convexshape of the second convex ribs 177, it is possible to isolate thewater, which is present in the vicinity 173 of the portions where theelectrical connection portions 134 are arranged, from the portions wherethe electrical connection portions 134 are arranged. Accordingly, it ispossible to improve the waterproof property of the battery pack 160 byrestricting the intrusion of water into the housing case 111 from theelectrical connection portions 134.

Meanwhile, the battery pack according to the invention is not limited tothe above-mentioned embodiments, and appropriate portions of the batterypack may be modified as described below.

That is, the electrical connection portions 134 (the positive connectionportion 1341, the negative connection portion 1342, and the controlconnection portion 1343), the operation portion exposure window 1111,the hook portion exposure window 1112, and the intake-side vent hole 171have been exemplified as the communication opening of theabove-mentioned embodiment. However, the communication opening accordingto the invention is not limited to the above-mentioned embodiment, andany construction allowing communication with the inside of the housingcase from the outside of the housing case may correspond to thecommunication opening according to the invention. Further, thewater-introduction regulating portion according to the invention is alsonot limited to the above-mentioned embodiment, and any constructionrestricting the introduction of the water, which is present in thevicinity of the communication opening, into the communication openingmay correspond to the water-introduction regulating portion according tothe invention. That is, the water-introduction regulating portionaccording to the invention may be the inclined structure that makes thewater, which is present in the vicinity of the communication opening,flow in the direction away from the communication opening.Alternatively, it can be any structure that is formed in an uneven shapefor isolating water present in the vicinity of the communication openingfrom the communication opening. Furthermore, the “uneven shape” is notlimited to, for example, the above-mentioned convex ribs 175 and 177having the shape of protrusions, but may include a convex wall structurehaving convex ribs, a concave groove structure, and/or an appropriateuneven step shaped structure.

Meanwhile, the battery pack 160 of the above-mentioned fourth embodimentmay be positively provided with a water release passage as will bedescribed below. That is, the periphery 173 of the portion where theintake-side vent hole 171 is arranged is isolated due to the convexshapes of the above-mentioned first and second convex ribs 175 and 177,and therefore, water is apt to be collected due to these convex shapes.For this reason, a water release passage may be formed to allow releaseof water collected in the vicinity 173 of the portion where theintake-side vent hole 171 is arranged due to these convex shapesescapes. A structure having an appropriate shape may be proposed as thewater release passage, but, for example, the following structure may beused as the water release passage. That is, the hook clearance 179formed between the hook portion exposure window 1112 and the hookportion 148A of the male hook body 145A described in the above-mentionedthird embodiment may be configured as an inlet of the water releasepassage, and the above-mentioned operation portion exposure window 1111may be configured as an outlet of the water release passage. If the hookclearance 179 is configured as the inlet of the water release passage asdescribed above, water is temporarily introduced into the housing case111, flows along the base member 141A, and is discharged to the outsideof the housing case 111 from the operation portion exposure window 1111.Meanwhile, since the base member 141A isolates the housing case 111 andthe internal installation body 121 from each other as described above,water that has been temporarily introduced into the housing case 111 maynot reach the internal installation body 121. That is, it is possible toallow water to flow along the base member 141A and to be discharged tothe outside of the housing case 111 from the operation portion exposurewindow 1111. Meanwhile, other than using the operation portion exposurewindow 1111, the outlet of the water release passage may beappropriately formed. For example, a case communication hole, which isformed at the housing case 111 near the lower end of the base member141A and communicates the inside of the housing case 111 with theoutside of the housing case 111 in a vertical direction, may be formedas the outlet of the water release passage. If the outlet of the waterrelease passage is formed to allow for communication between the insideof the housing case 111 and the outside of the housing case 111 in thevertical direction as described above, water is easily discharged to theoutside of the housing case 111 from the lower portion of the housingcase 111.

DESCRIPTION OF REFERENCE NUMERALS

-   -   10, 10A: battery pack    -   20: housing case    -   201: support lower surface    -   21, 21B: case body    -   211: bottom wall portion    -   212: side wall portion    -   221: outer surface    -   222: inner surface    -   223: bottom surface    -   23: rib    -   231: support rib    -   232: air guide rib    -   233: foreign material-introduction restricting rib    -   25, 25A, 25B: drain hole (drainage function-shape portion)    -   261: outer end edge    -   262: inner end edge    -   27, 27B: drain passage (drainage function-shape portion, flow        guide means)    -   28: drawing groove (drainage function-shape portion, draw guide        means)    -   31: upper cover member    -   32: slide guide portion    -   33: connection opening    -   34: hook-exposure opening    -   35: air vent opening    -   39: screw member    -   40: battery pack body    -   41: battery cell    -   42: electrode    -   45: lead plate    -   46 (461, 462, 463): left lead plate    -   47 (471, 472, 473): right lead plate    -   51: connection control board    -   52: control board    -   53: connection terminal portion    -   55: male hook mechanism    -   56: hook-type structure    -   C: clearance    -   F: placement surface

The invention claimed is:
 1. A battery pack configured to be mounted ona tool body of an electric tool as a power source of the electric tool,the battery pack comprising: a housing case configured as an outercover, the housing case including: a side wall portion having an upperend and a lower end, a bottom wall portion having an outercircumferential edge, and a joint portion connecting the lower end ofthe side wall portion and the outer circumferential edge of the bottomwall portion; a plurality of battery cells disposed in the housing case,and a water drain hole provided to the housing case, the water drainhole having an inner end edge and an outer end edge, the inner end edgecommunicating with an internal space defined in the housing case, andthe outer end edge being opened to an outside of the housing case;wherein the outer end edge is located at the joint portion, and at leasta part of the outer end edge is opened to the outside in a horizontaldirection parallel to an extending direction of the bottom wall portion.2. The battery pack according to claim 1, wherein: the outer end edge ofthe water drain hole includes a first part and a second partrespectively positioned on an inner side and an outer side with respectto the horizontal direction; and the second part is opened to theoutside in the horizontal direction.
 3. The battery pack according toclaim 2, wherein: the bottom wall portion includes an outer side surfaceextending in the extending direction; and the second part of the outeredge of the water discharge hole is higher than the first part withrespect to a vertical level with reference to the outer side surface. 4.The battery pack according to claim 3, wherein the first part ispositioned within a substantially same plane as the outer side surface.5. The battery pack according to claim 1, wherein the at least a part ofthe outer end edge of the water drain hole is opened to the outside inthe horizontal direction at the joint portion.
 6. The battery packaccording to claim 5, wherein: the joint portion includes an inclinedwall portion extending obliquely upward from a side of the bottom wallportion toward a side of the side wall portion; and the at least a partof the outer end edge of the water drain hole is opened to the outsidein the horizontal direction at the inclined wall portion.
 7. The batterypack according to claim 1, wherein the bottom wall portion has asubstantially rectangular shape; and wherein the housing case comprisesa plurality of water drain holes arranged symmetrically with respect toa central point of the substantially rectangular shape.
 8. A batterypack configured to be mounted on a tool body of an electric tool as apower source of the electric tool, the battery pack comprising: ahousing case configured as an outer cover, the housing case including; aside wall portion having an upper end and a lower end, a bottom wallportion having an outer circumferential edge, and a joint portionconnecting the lower end of the side wall portion and the outercircumferential edge of the bottom wall portion, a plurality of batterycells disposed in the housing case, and a water drain hole provided tothe housing case, the water drain hole having an inner end edge and anouter end edge, the inner end edge communicating with an internal spacedefined in the housing case, and the outer end edge being opened to anoutside of the housing case; wherein the outer end edge rises by apredetermined distance toward the inside the housing such that the outerend edge is opened at an outer surface of the housing case in both adownward direction and a horizontal direction parallel to an extendingdirection of the bottom wall portion.
 9. The battery pack according toclaim 8, wherein: the joint portion includes an inclined wall portionextending obliquely upward from a side of the bottom wall portion towarda side of the side wall portion; and the outer end edge of the waterdrain hole is opened in the horizontal direction at an outer surface ofthe inclined wall portion.
 10. A battery pack configured to be mountedon a tool body of an electric tool as a power source of the electrictool, the battery pack comprising: a housing case configured as an outercover, the housing case including; a side wall portion having an upperend and a lower end, a bottom wall portion having an outercircumferential edge, and a joint portion connecting the lower end ofthe side wall portion and the outer circumferential edge of the bottomwall portion, a plurality of battery cells disposed in the housing case,and a water drain hole provided to the housing case, the water drainhole having an inner end edge and an outer end edge, the inner end edgecommunicating with an internal space defined in the housing case, andthe outer end edge being opened to an outside of the housing case;wherein the outer end edge is opened to the outside in a horizontaldirection parallel to an extending direction of the bottom wall portionat the joint portion.
 11. The battery pack according to claim 10,wherein: the outer end edge of the water drain hole includes an upperend portion and a lower end portion defining an open area opened in thehorizontal direction; the upper end portion of the outer end edge ispositioned at a higher level than a plane within which an outer sidesurface extends in the extending direction; and the lower end portion ofthe outer end edge is positioned at a lower level than the upper endportion.
 12. The battery pack according to claim 11, the open areaincludes an area part positioned at a lower level than the plurality ofbattery cells disposed within the housing case.
 13. The battery packaccording to claim 10, wherein: the joint portion includes an inclinedwall portion extending obliquely upward from a side of the bottom wallportion toward a side of the side wall portion; and the outer end edgeof the water drain hole is opened to the outside in the horizontaldirection at an outer surface of the inclined wall portion.
 14. Abattery pack configured to be mounted on a tool body of an electric toolas a power source of the electric tool, the battery pack comprising: ahousing case configured as an outer cover, the housing case including: aside wall portion having an upper end and a lower end, a bottom wallportion having an outer circumferential edge, and a joint portionconnecting the lower end of the side wall portion and the outercircumferential edge of the bottom wall portion; a plurality of batterycells disposed in the housing case, and a water drain hole provided tothe housing case, the water drain hole having an inner end edge and anouter end edge, the inner end edge communicating with an internal spacedefined in the housing case, and the outer end edge being opened to anoutside of the housing case; wherein the outer end edge is located atthe joint portion or proximal to the joint portion, and the outer endedge rises by a predetermined distance toward the inside the housingsuch that at least a part of the outer end edge is opened to the outsidein a horizontal direction parallel to an extending direction of thebottom wall portion.
 15. A battery pack configured to be mounted on atool body of an electric tool as a power source of the electric tool,the battery pack comprising: a housing case configured as an outercover, the housing case including: a side wall portion having an upperend and a lower end, a bottom wall portion having an outercircumferential edge, and a joint portion connecting the lower end ofthe side wall portion and the outer circumferential edge of the bottomwall portion; a plurality of battery cells disposed in the housing case,and a water drain hole provided to the housing case, the water drainhole having an inner end edge and an outer end edge, the inner end edgecommunicating with an internal space defined in the housing case, andthe outer end edge being opened to an outside of the housing case;wherein the outer end edge is located at the joint portion or proximalto the joint portion, and the outer end edge rises by a predetermineddistance toward the inside the housing such that a clearance is formedbetween the outer end edge and an outer surface of the bottom wallportion.
 16. A battery pack configured to be mounted on a tool body ofan electric tool as a power source of the electric tool, the batterypack comprising: a housing case configured as an outer cover, thehousing case including; a side wall portion having an upper end and alower end, a bottom wall portion having an outer circumferential edge,and a joint portion connecting the lower end of the side wall portionand the outer circumferential edge of the bottom wall portion, aplurality of battery cells disposed in the housing case, and a waterdrain hole provided to the housing case, the water drain hole having aninner end edge and an outer end edge, the inner end edge communicatingwith an internal space defined in the housing case, and the outer endedge being opened to an outside of the housing case; wherein the waterdrain hole is opened to the outside in a horizontal direction parallelto an extending direction of the bottom wall portion at the jointportion.
 17. The battery pack according to claim 1, wherein the outerend edge rises toward the inside the housing.
 18. The battery packaccording to claim 17, wherein the water drain hole is opened to theoutside in the horizontal direction parallel to the extending directionof the bottom wall portion.
 19. The battery pack according to claim 17,wherein a clearance is formed between the outer end edge and an outersurface of the bottom wall portion.
 20. The battery pack according toclaim 1, wherein the at least a part of the outer end edge is alsoopened in a downward direction.
 21. The battery pack according to claim14, wherein the water drain hole is opened to the outside in thehorizontal direction parallel to the extending direction of the bottomwall portion.
 22. The battery pack according to claim 14, wherein aclearance is formed between the outer end edge and an outer surface ofthe bottom wall portion.
 23. The battery pack according to claim 8,wherein the water drain hole is opened to the outside both in thedownward direction and the horizontal direction.
 24. The battery packaccording to claim 8, wherein a clearance is formed between the outerend edge and an outer surface of the bottom wall portion.